Holddown for punch presses, shears, or the like



F 1933. F. E. MUNSCHAUER ,8 565 HOLDDOWN FOR PUNCH PRESS ES, SHEARS, ORTHE LIKE Filed Ap'ril 18, 1952 C; Shee ts-Sheet l Feb. 21, 1933.

F. MUNSCHAUER 1,898,565 HOLDDOWN FOR PUNCH PRESSES, SHEARS, OR THE LIKEFiled April 18, 1932 3 Sheets-Sheet 2 BmwwrEYPaw Feb. 21, 1933.1,898,565

HOLDDOWN FOR PUNCH PRESSES, SHEARS; on THE LIKE F. E. MUNSCHAUER 3Sheets-Sheet 3 Filed April 18, 1932 Patented Feb. 21, 1933 Umrso srATEsPATENT- OFFICE FREDERICK E. MUNSOHAUER, OF BUFFALO, NEW YORK, ASSIGNOBTO NIAGARA MACHINE a TOOL WORKS, OF BUFFALO, NEW YORK, A. CORPORATION OFNEW YORK HOLDIDOWN FOR PUNCH PRESSES, SEEARQOR THE LIKE Applicationfiled April 18,

This invention relates to a holddown for shearing machines, punchpresses or the like, and more particularly to a device forpressing upona sheet of metal in a punch press at a multiplicity of points during theshearing or stamping operation so that the sheet of metal is held inproper position during the stamping or shearing operation and does notget out of alinement.

One of the principal objects of this invention is to provide such aholddown device which presses upon a sheet of metal in the shears at amultiplicity of places and exerts a uniform pressure at each pointregardless is of variations in the thickness of the metal or otherconditions and at the same time is operable from a single' source sothat its operation can be controlled from one place.

Another object is to provide such a holdao down which can be operatedthrough fluid pressure and at the same time avoids almul tiplicity ofcylinders with the consequent danger of leakage which has been thedreadvantage of such fluid pressure systems heretofore used, the presentinvention proposing a master cylinder whichcontrols each of the holddowndevices through mechanical connections.

Another object is to provide such a holddown which can be readily usedin'connec- P tion with other controls or with an automatic control suchas a cam which is synchronized with the operation of the shears.

Another purpose is to provide a multiplicity of spring feet or pressermembers which are operated in unison and each of which is so designedthat it exerts the required pressure to hold the metal in position andat the same time yields so that the other spring feet can be broughtdown far enough to also engage the sheet of metal with the proper;pressure. These spring feet are so designed that they are extremelysimple in construction, are compact, are easily operated 1922. SerialNo. 605,983.

and will not get out of order under conditions of severe and constantuse.

In the accompanying drawings:

Figure 1 is a front elevation of a power shears showing the sameequipped with a w holddown device embodyin my invention, the holddownfeet in thlsj form of the invention being operated from a mastercylinder at one end of the machine.-

Figure 2 is an end elevation viewed from the right hand end of Fig. 1.

Figure 3 is aside elevation of one ofthe holddown units of which amultiplicity areshown in Fig. 1. FFigure 4 is a section taken on line4-4,

Figures 5 and 6 are sections taken on the correspondingly numbered linesof Fig. 4.

Figure 7 is a side elevation viewed from the left hand side of Fig. 1and showing a 5 modification of the master control for the holddownunits, which master control includes a cam synchronized with theoperation of the press.

Figure 8 is a fragmentary view similar to 7 Fig. 1 and showing themodified form of the invention illustrated in Fig. 7.

Figure 9 is a fragmentary top plan view of the form of the inventionshown in Fig.

7 and showing the rock arm operated by the 15 cam.

Similar reference numerals refer to similar parts in each of the severalviews.

The invention is illustrated in connection with a power shears althoughit will be under- 30 I stood that the invention can be employed anywherewhere it is desirable to hold down a piece of metal upon a table whilesome operation is being performed upon it. The shears shown consist ofstandards 10 and 11 which support a bed 12, a cross plate 9 and avertically reciprocating head 13 carrying the knife 14, the sheet ofmetal, fiber, etc. to be out being placed upon the bed 12 and beingsheared by the knife 14.- as the head 13 is reciprocated. The standards10 and11 also carry a drive shaft 15 at one end of which is arranged thedriving pulley 16 and at the other end a pinion 17 which meshes with alarge gear 18. The gear wheel 18 is fast on a cam shaft 19 which isjournaled in the standards 10 and 11 and carries a pair of cams 20.

ese cams are connected by straps 21 with the cutter head 13 so that asthe cam shaft 19 turns the cutter head is reciprocated vertically, thiscutter head being suitably guided in the endheads 10 and 11 and thecross plate 9.

The present invention consists of a plurality of spring holddown unitsindicated generally at 22 which are operated in unison through thereciprocation of a rod 23, this rod passing through the casings of eachof the units 22 and having one end projecting yond the end of thestandard 10. These units 22 are secured to the underside of the crossplate 9 by screws or in any other suitable manner and each is preferablyconstructed as follows:

The casing for each of the spring holddown units 22 preferably comprisesa body portion 24 and a cap 25 which is secured to one side of the bodyportion by screws 26 or in any other suitable manner. As best shown in Fig. 6, the rod 23 slides in a slideway 27 provi ed in the body portions24 of each casing and is provided at each of the units 22 with aplurality of teeth 28 so that the rod 23 is, in effect, a rack. Theseteeth are provided adjacent each unit 22 and each group of teeth engageswith a pinion 29 which is integral with cross shaft 30, this cross shaftbeing journaled at one end in the body 24 of the casing and at its otherend is journaled in the cap 25. Within the body portion 24 this shaft 30carries another integral pinion 31 which meshes with teeth 32 providedin the side of a sleeve 33. This sleeve is slidabiiy carried in avertical slideway 34 in the b0 y portion 24 and is provided with acylindrical bore 35. In the lower part of this cylindrical bore 35 andpro'ecting downwardly from the lower end of the sleeve 33 is acylindrical holddown foot 36 which is adapted to engage the metal on thebed 12 of the power shears. Extending up from this holddown foot 36 is astem 37 which extends upwardly through the sleeve 33 and at its upperend is provided with a nut 38 which limits the downward movement of theholddown foot 36 but permits it to move upwardly. Interposed between thefoot 36 and the upper end of the sleeve 33 is a helical compressionspring 39, this spring holding the foot'36 in a downward positionrelative to the sleeve 33 and holding the nut 38 in engagement with theupper end of the sleeve.

It is apparent that upon reciprocating the rod 23 in one direction itsteeth 28 turn the pinions 29 and 31 and thereby reciprocate the sleeve33 downwardly. This continues until the foot 36 engages the piece ofmetal, fiber, or other sheet material on the bed 12 after which, if thereciprocation of the rod 23 is continued, the continued movement of thesleeve 33 will operate to compress the spring 39 but will not force thefoot 36 further although exerting additional pressure on the foot. Witha plurality'of units 22 it is therefore apparent that the springs 39will equalize any differences in their action and W111 compensate forany inequalities in the surface of the piece of sheet metal being helddown since these springs will give and yieldmgly hold thefeet 36 againstthe surface of the sheet.

In the form of the invention shown in Fig. 1, the master rod 23 isreciprocated by fluid pressure, this rod extending through one head of acylinder 40 and being connected with a piston 41 therein. Fluid isadmitted to the cylinder 40 on opposite sides of the piston 41 by meansof pipes 42 and 43. It is therefore apparent that by suitablemanipulation of the valves (not shown) the piston- 41 can bereciprocated to move the rod 23 to either press the several holddownfeet of the unit 22 into engagement with the sheet of metal on the bed12 or to withdraw these feet therefrom.

Instead of providin a master cylinder to control the reciprocation ofthe master rod '23 this can be effected from a cam which is synchronizedwith the operation of the shear. Such a form of the invention is shownin Figs. 7-9 in which the controlling cam 44 is mounted at one end ofthe main cam shaft 19 and is engaged by a roller 45, this roller beingcarried by a rock arm 46. One end of this rock arm 46 is pivoted to thestandard 10 as indicated at 47 and the free end is pivotally connectedto a connecting rod 48. The

lower end of this connectingrod 48 is con-- nected to abell crank lever49, this bell crank lever being pivoted at its center to the standard 10as indicated at 50 and the other arm of this. bell crank lever beingconnected by means of a coupling 51 with the end of the master rod 23.his coupling is preferably such that it can be adjusted so as to varythe distance between the bell crank lever and the rod 23., It isapparent that each time the cam 44 reciprocates, the bell crank lever 49is moved to reciprocate the holddown feet of the units 22. The constantengagement of the roller 45 with both the salient and low parts of thecam sion spring 52 which is interposed between a nut 53 at the free endof the rod 23 and the endmost unit 22 so ly urges the rod 23 in theposition in which the holddown feet are held in their elevated positionwhile the salient portion of the cam 44 forces these holddown feetagainst the resistance of the spring 52, down and into en- 44 is insuredby a compres-.

that this spring constantmeans gagement with the sheet of metal on thebed 12 From the foregoing it is apparent that the present inventionprovides a very simple and durable means for holding a sheet of metal onthe bed of a shear or the like at a plurality of places and at the sametime permits of all of these holddown units to be released or placed inoperation simultaneously from a' single controlling source. The holddownalso does not interfere with the free operation of the machine, iscompact, will not get out of order, and can be easily adapted to eitherautomatic operation in synchronism with the shear or to hand controlledoperation.

I claim as my invention:

1.. A holddown mechanism for shears or the like, comprising a pluralityof holddown feet movably mounted on the shear frame for movement towardand from the bed thereof, a movable bar arranged adjacent said feet,means for moving said bar and means opcratively connecting said bar andholddown feet for simultaneously moving each of said feet into and outof operative position.

2. A holddown mechanism for shears or the like, comprising a pluralityof holddown feet movably mounted on the shear frame for movement towardand from the bedthereof,

a longitudinally reciprocable bar arranged adjacent said feet, means forreciprocatlng said bar and means operatively connecting said bar andholddown feet for simultaneously moving each of said feet into and outof operative position.

3. A holddown mechanism for shears or the like, comprising a pluralityof vertically reciprocable holddown feet mounted on the shear frame formovement toward and from the bed thereof, a movable bar arrangedadjacent said feet and means operatively connecting said bar and holddown feet for simultaneously moving each ofsaid feet into and out ofoperative position.

4. A holddown mechanism for shears or the like, comprising a pluralityof easing members mounted on the frame of said shear adjacent the bedthereof, and each of said casings being provided with a slideway, aholddown foot arranged in each of said slideways and movable toward andfrom the bed of said punch press, a movable bar arranged adjacent saidholddown feet, means for moving said bar and means for simultaneouslyreciprocating each of said holddown feet into and out of operativeposition through motion derived from said bar.

5. A holddown mechanism for shears or -the like, comprising a pluralityof carriers each having a recess, a holddown foot'slidably arranged insaid recess and projecting outwardlytherefrom, means limiting theoutward movement of said foot, a spring in said recess and urging saidfoot into its projected position, means for movably supporting feet intoand out of operative engagement with the :sheet material on the bed ofthe?o shear.

6. A holddown mechanism for shears or the like, comprising a pluralityof sleeves open at one end, means for supporting said sleeves forlongitudinal, vertical, reciprocatory movement, a holddown foot fittedin said sleeve and projecting outwardly therefrom, a stem on said footand projecting through the end of said sleeve opposite its open end, anabutment at'the projecting end of said stem to limit the outwardprojection of said foot, a spring in said sleeve around said stem andurging said foot to project outwardly and means for simultaneouslyreciprocating each of said carriers to move said feet-into and out ofoperative engagement with the sheet material on the bed of the shear.

7. A holddown mechanism for shears or the like, comprising a pluralityof longitudinally reciprocable holddown feet mounted on the punch pressframe for movement toward and from the bed thereof, a movable bararranged adjacent said feet and means, including a pinion forsimultaneously moving each of said feet into and out of operativeposition.

8. A holddown mechanism for shears or the like, including a plurality oflongitudinally movable holddown devices having a row of teeth andarranged to move toward and from the bed thereof, a rack arrangedadjacent said members, means for reciprocating said rack and pinion"means connecting said rack with the teeth of said devices,

the like, including a plurality of casings,-

each of said casings being provided with slideways arranged at an angleto one another, a rack extending through the corresponding slideways ofeach of said casings, pinion means journaled in each of said casings andengaging the corresponding teeth of said rack, and a holddown devicearranged in the other slideway of each casing and provided with a row ofteeth also engaging pinion means whereby assaid rack is reciprocated,said holddown devices are simultaneously moved into and out of operativeposition.

10. A holddown mechanism for shears or the like, including a pluralityof casings, each of said casings being provided with slideways arrangedat an angle to one another, a rack extending. through the correspondingslideways of each of said casings, pinion means journaled in each ofsaid casings and engaging the corresponding teeth of said rack, a sleevehaving external teeth arra ed in the other slideways of each cas ing, te teeth of said sleeve also engaging said pinion means, a holddown footarrange in said sleeve and spring means arranged in said sleeve andurging said holddown foot into an outwardlyv projecting position, theholddown feet associated with the several casings being simultaneouslymoved into and out of operative position upon reciprocating said rac Intestimony whereof I hereby aiiix my' signature.

FREDERICK E. MUN SCHAUER,

